Oil Pressure for 350Mag

At a Cold start it’ll be higher at idle than it would be when idling fully warmed up.

What numbers are you seeing?

I see 48-50 psi cruising at 3-3500 rpm. I don’t remember the hot idle pressure, probably somewhere in the 20’s, I’ll check next time out.
 
Should be 10 pounds for every 1,000 rpm thats ur min Safe Range...... Any less ur gonna start burning up bearings.... So for 4,000 rpms u want 40lbs
 
Cold start heard clicking from starboard motor. Pressure is fluctuating around 34 to 44 Not staying consistent like port at 43. Mechanic thinks it is about to throw a crank bearing.
 
If your mechanic used the exact words “throw a crank bearing” I would question his qualifications.

Lack of lubrication can cause a bearing to “spin”.
A crankshaft bearing that rotates (or spins) slightly will block off its own oil supply and destroy that particular bearing very quickly.

A connecting rod bearing that spins will have already become severely worn, from lack of lubrication or a loose connecting rod bearing cap.

In some designs, That “spun” connecting rod bearing could also block off the oil supply to the wrist pin and cylinder wall.

A loose connecting rod bearing sounds like a dull knocking sound deep down in the block, which can momentarily disappear when you quickly snap the throttle closed from 1,800 or so rpm. Not easy to diagnose down in the bilge, much easier on a car engine.

Now for some good news..
Fluctuations in the oil pressure gauge could simply be a bad oil pressure sender.
 
"Throwing a crank bearing", was my description. Probably a bad chose of terminology. Mechanic was on the vessel with me and we both heard it.
 
I was taking pictures today of my SmartCraft, I am reading 63 psi on both engines, right around 4k rpm, I have 350mag horizon MPI, and I have v-drives, not sure if that makes any difference or not.
 
Siboatguy said:
Should be 10 pounds for every 1,000 rpm thats ur min Safe Range...... Any less ur gonna start burning up bearings.... So for 4,000 rpms u want 40lbs
Click to expand...
That is exactly what GM says for autos, and since these are GM blocks, I agree 100% with that statement. I remember looking at a 2002 320 with 350 engines and one had 2 psi oil press at idle - the broker said "oh, that's fine" - yea right. The future buyer lost that engine 20 hrs later...
 
Thanks! I have V drives. We'll find out soon what the issue is. It is being pulled out of the water this week.
 
My last jet boat had a 5.7 Kodiak (Vortec) with a bad lifter that would give me problems after a hard pull. Oil pressure would drop from about 30 to 20 at idle along with developing a loud tick. Actually thought it was a rod bearing the first time. After cooling down for a short period it would pick back up to all normal again. It did it 3 times before I installed a new set and was never an issue again. Talked to several other mechanics about it and they didn't think it was possible but is what it is.
 
Should also add that if you have a mechanical bearing failure, you will find contamination in the filter if you cut it open. My filter was clean when I checked it.
 
Espos4 said:
At a Cold start it’ll be higher at idle than it would be when idling fully warmed up.

What numbers are you seeing?

I see 48-50 psi cruising at 3-3500 rpm. I don’t remember the hot idle pressure, probably somewhere in the 20’s, I’ll check next time out.
Click to expand...


Out for a ride today.
I had right around 30 psi at idle after a 20 minute cruise.
 
oil pressure fluctuating at a steady load and rpm is not correct . lower pressures at hot oil are good , correct and not an issue .
 
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